The approaching anniversary of the 9/11 terrorist attacks/crime against humanity invites thoughts on shared vulnerability and common purpose. It is important to remember that, prior to that day, enthusiasts of U.S. post-cold war primacy were calling upon the country to “seize the unipolar moment.” Such euphoria was quickly grounded by the realization that even the most powerful country was vulnerable to forces and developments beyond its borders—a feeling of vulnerability which was quickly shared by our fellow human beings, following the traumatic experiences in, among other places, Madrid, London, Beslan, Bali, and Mumbai. The loss and pain transcends borders, and so should the response. Challenges to human security, such as those posed by transnational terrorism, necessitate multilateral, not unilateral action—action which must be both effective and reflective of the values that make us who we are. Nothing will constitute a more fitting tribute to all those who lost their lives that day than a commitment to reaffirm our common humanity in response to an act of extraordinary inhumanity.